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United States Patent |
5,154,870
|
Urui
,   et al.
|
October 13, 1992
|
Thermoplastic resin sheet manufacturing process and its apparatus
Abstract
An apparatus and process for making extruded colored thermoplastic resin
sheets is shown and described. In this process, a colored thermoplastic
sheet material is encapsulated within a clear material. The colored
material as it merges with the clear material is subjected to a clear
material flow direction vector which causes the colored material to spread
or become wider than the color material orifice. The spreading due to
clear material flows in a widthwise direction produces a uniform taper to
the colored edge, and the point at which the colored material stops and
the finished product is barely perceptible. In this apparatus, a clear
flow thermoplastic extrusion die has placed within its manifold a colored
material distributing inner pipe which has an orifice for inserting color
material into the flow of the clear material. The color insertion occurs
at a point where the clear material has a flow vector in the widthwise
direction and towards the clear portion of the finished product.
Inventors:
|
Urui; Yasuhiro (Kusatu, JP);
Omizu; Morimasa (Okayama, JP)
|
Assignee:
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Sekisui Kagaku Kogyo Kabushiki Kaisha (JP)
|
Appl. No.:
|
727222 |
Filed:
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June 26, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
264/173.18; 264/75; 264/245; 425/131.1; 425/133.5; 425/462 |
Intern'l Class: |
B29C 047/04 |
Field of Search: |
264/171,75,245
425/131.1,133.5,462,224
|
References Cited
U.S. Patent Documents
3354025 | Nov., 1967 | Aykanian et al. | 264/245.
|
3583032 | Jun., 1971 | Stafford | 425/133.
|
3715420 | Feb., 1973 | Kiyono et al. | 264/171.
|
4316868 | Feb., 1982 | Esposito et al. | 264/245.
|
4476075 | Oct., 1984 | Brinkmann et al. | 264/245.
|
4562023 | Dec., 1985 | Pabst et al. | 264/75.
|
4671913 | Jun., 1987 | Gen et al. | 264/171.
|
4753766 | Jun., 1988 | Pinsolle | 264/245.
|
Foreign Patent Documents |
0287861 | Oct., 1988 | EP | 264/171.
|
51-109954 | Sep., 1976 | JP | 264/171.
|
55-135642 | Oct., 1980 | JP | 425/133.
|
Primary Examiner: Thurlow; Jeffery
Claims
What is claimed is:
1. A process for making thermoplastic resin sheets having a colored section
within a first resin section comprising the steps of:
(a) using an extrusion mold for manufacturing thermoplastic resin sheets,
said mold having along the widthwise direction a first resin section
manifold for the first thermoplastic resin, and a colored resin section
which is within the first resin section manifold;
(b) introducing said first resin into said first resin section manifold,
and colored resin into a colored resin passage;
(c) extruding said colored resin and said first resin through a slit-shaped
die orifice;
(d) providing a land between the manifold and the slit-shaped die orifice;
(e) providing an opening in the colored resin passage in a position where
there is flow of said first thermoplastic resin in the widthwise direction
within the manifold and in the direction away from said colored section.
2. An apparatus for manufacturing thermoplastic resin sheets having along
the widthwise direction of the sheet a first thermoplastic resin layer in
which a colored thermoplastic resin band is encapsulated;
(a) said apparatus having an extrusion mold and an inner pipe, and said
extrusion mold having a manifold, side plates provided on both sides of
the manifold widthwise, a first resin feed passage for feeding first
thermoplastic resin into said manifold, a slit-shaped die orifice through
which said first thermoplastic resin is extruded, and a land provided
between the manifold and the slit-shaped die orifice;
(b) wherein said inner pipe is located within said manifold, and wherein
each end of the inner pipe is supported by one of said side plates;
(c) said inner pipe having a colored resin feed passage for feeding colored
thermoplastic resin within the manifold, wherein said colored resin feed
passage opening is located in a position where there is flow of the first
thermoplastic resin in the widthwise direction and away from said resin
belt within the manifold.
3. The apparatus in accordance with claim 2, wherein an opening for said
first resin feed passage and an opening for the colored resin feed passage
are elongated and extend in the direction of the widthwise flow of said
first thermoplastic resin.
4. The apparatus of claim 2, wherein said inner pipe is cylindrical.
5. The apparatus according to claim 2, wherein the flow away from the resin
belt occurs between two layers of said first resin.
6. An apparatus for manufacturing thermoplastic resin sheets having along a
widthwise direction a first resin section comprising a first thermoplastic
resin and a colored band section made of colored thermoplastic resin which
is encapsulated within the first thermoplastic resin layer, comprising in
combination:
an extrusion mold and die plate said extrusion mold having;
(a) a manifold, a first resin feed passage for feeding the first
thermoplastic resin into said manifold, and a slit-shaped die orifice
through which said first thermoplastic resin is extruded out of the
manifold;
(b) a pipe inside of said manifold fastened to walls at the end of the
manifold, and said pipe having a nozzle that feeds colored thermoplastic
resin into the manifold; and
(c) wherein an opening of said nozzle is provided in a position having flow
of the first thermoplastic resin widthwise within the manifold and in a
direction away from said colored belt section.
7. The apparatus of claim 6, wherein there is an opening for said first
resin feed passage and an opening for the colored resin feed passage in
this order in the direction of the flow widthwise of said first
thermoplastic resin.
8. The apparatus of claim 6, wherein said manifold and said pipe have
inlets which are at the same end of said manifold.
9. An apparatus for extruding a thermoplastic sheet having a colored
portion and a first portion comprising in combination:
(a) a first extrusion die having a slit for extruding said first portion;
(b) said first extrusion die having a passage through which said first
portion flows in a widthwise direction, and a slit-shaped die orifice
extending in the widthwise direction;
(c) a color extruding die having an orifice extending in said widthwise
direction and located within said first extrusion die for introducing said
colored material into said first material to form two layers of said first
material; and
(d) wherein said color extruding orifice has all of its sides which extend
in a widthwise direction not parallel to each other.
10. The apparatus according to claim 6, wherein said inner pipe is
cylindrical.
11. The apparatus according to claim 3, wherein said inner pipe is
cylindrical.
12. The apparatus according to claim 7, wherein said pipe is cylindrical.
13. The apparatus according to claim 2, wherein said pipe is conical in
shape and the distance from said manifold to said pipe varies as a
function of the widthwise location.
14. The apparatus in accordance with claim 2, wherein said inner pipe has
at least one portion of said feed passage opening closer to said manifold
than another.
15. The apparatus according to claim 9, wherein the widthwise portion of
the flow from the first extrusion die orifice is in a direction which is
away from said colored portion, whereby said colored portion is carried by
said first portion widthwise flow in a direction which makes the colored
portion wider in said widthwise direction than said color extruding
orifice.
16. An apparatus for the extrusion of a thermoplastic polymer having a
color band, comprising in combination:
(a) a first extrusion mold having a manifold and a slit dye orifice;
(b) an inner passage located in the extrusion mold manifold and having an
orifice;
(c) means for supplying a first resin to said manifold and means for
supplying a second color resin to said inner passage;
(d) spacing said inner passage a sufficient distance from said manifold
slit die orifice to permit flow of the first material in a widthwise
direction wherein said widthwise direction flow causes spreading of said
colored resin as it passes between said orifice and said slit-shaped dye
orifice; and wherein said spreading increases the width of said colored
resin as compared to the inner passage orifice width.
17. The apparatus in accordance with claim 16, wherein said inner passage
is a pipe.
18. The apparatus in accordance with claim 16, wherein said inner passage
is a cylindrical pipe.
19. The apparatus in accordance with claim 16, wherein said inner passage
is a conical pipe.
20. The apparatus in accordance with claim 16, wherein said extrusion
manifold has a circular cross-section.
21. The apparatus in accordance with claim 16, wherein said extrusion
manifold has a generally triangular cross-sectioned shape.
22. The apparatus in accordance with claim 21, wherein said inner passage
is formed in a plate extending from the base of said triangle, and where
the slit-shaped die orifice is located at a top of said triangle.
23. The apparatus in accordance with claim 16, wherein said passage is in a
die plate.
24. A process for the extrusion of a thermoplastic polymer sheet with a
gradient color band incorporated therein which comprises:
(a) providing a first extrusion mold having a manifold and a slit die
orifice;
(b) providing an inner passage located in the extrusion mold manifold and
having an orifice;
(c) providing means for supplying a first resin to said manifold, and means
for supplying a second color resin to said inner passage;
(d) spacing said inner passage a sufficient distance from said manifold
slit die orifice to permit flow of the first resin in a widthwise
direction wherein said widthwise direction flow causes spreading of said
colored material as it passes between said orifice and said slit-shaped
die orifice;
(e) feeding a main flow of molten thermoplastic resin to the manifold and a
colored flow of the same resin to the passage;
(f) extruding both flows simultaneously to form a layer of color resin that
is greater in width than the orifice in said passage, which tapers in
thickness as a result of widthwise flow of the first resin, and which is
completely encapsulated within a main flow molten resin; and
(g) extruding the combined flows through the slit-shaped die orifice to
produce a shape with an encapsulated gradient color band.
25. The process according to claim 24, in which the inner passage is
inserted into the manifold at the same end as the first resin is inserted
into said manifold.
26. The process according to claim 24, wherein said passage orifice has
sides which are not parallel in the direction of the slit-shaped dye
orifice.
27. A process for the extrusion of a thermoplastic polymer sheet with a
gradient color band incorporated therein which comprises:
(a) providing a first extrusion mold having a manifold and a slit die
orifice;
(b) providing an inner passage located in the extrusion mold manifold and
having an orifice;
(c) providing means for supplying a first resin to said manifold, and means
for supplying a second color resin to said inner passage; and
(d) spacing said inner passage a sufficient distance from said manifold
slit die orifice to permit flow of the first resin in a widthwise
direction.
28. An apparatus for the extrusion of a thermoplastic polymer having a
color band, comprising in combination:
(a) a first extrusion mold having a manifold and a slit die orifice:
(b) an inner passage located in the extrusion mold manifold and having an
orifice;
(c) means for supplying a first resin to said manifold and means for
supplying a second color resin to said inner passage;
(d) spacing said inner passage a sufficient distance from said manifold
slit die orifice to permit flow of the first material in a widthwise
direction wherein said widthwise direction flow causes spreading of said
colored resin as it passes between said orifice and said slit-shaped die
orifice; and
wherein the clear flow is sufficiently great in a widthwise direction to
cause at least a portion of the colored resin to flow in a general
widthwise direction and to cause the colored material to increase in width
greater than the width of the orifice for the colored passage, thereby to
produce a gradual transition from colored to clear.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process that uses an extrusion mold to
manufacture thermoplastic resin sheets having along the widthwise
direction a first (clear) resin section comprising a first thermoplastic
resin and a colored section in which a colored band made of the colored
thermoplastic resin is encapsulated within the first resin layer formed
with the first thermoplastic resin, and an apparatus for manufacturing
such sheets.
The windshield glass used in automobiles, and airplanes, and the laminated
glass used in windows of buildings, and elsewhere comprise a middle film
of plasticized polyvinyl butyral sandwiched between two facing glass
plates. Such laminated glass has great strength and fragments do not fly
about even if the glass is broken.
2. The Prior Art
A method of manufacturing the middle films used in such laminated process
is known. This method feeds to an extrusion mold polyvinyl butyral that
has been heated to melting while being mixed in a cylinder, and extrudes
it from the extrusion mold to obtain a thin-film for use in the middle of
the glass layers.
The middle film so obtained is colorless and transparent, and most of the
light passes through this middle film. In order to restrict the
transmission of light, attempts have been made to set up a band-shaped
colored section along part of the width of the middle film.
For example, in the thermoplastic resin sheets used in automobile
windshields, the amount of sunlight shining on the driver through the
windshield can be reduced by creating a colored section with a color
gradient at the top of the sheet.
The colored section is usually set up in the sheet by printing a
band-shaped colored section on the surface of a film made of polyvinyl
butyral. However, when the colored section is formed by applying ink,
there is the disadvantage that the colored section peels away easily from
the film surface. Moreover, after the polyvinyl butyral resin film has
been formed, the colored section must be formed, and the manufacturing
process is complex, and the equipment is unavoidably large scale.
In Japanese patent publication Hei-l-43606 (U.S. Pat. No. 4,316,868), a
process is disclosed for manufacturing sheets with a certain width colored
band encapsulated within the thermoplastic resin. In this process, the
thermoplastic resin main flow goes into the manifold and is extruded
through an extrusion passage and from a slit-shaped die extrusion mold,
and colored thermoplastic resin is extruded from a probe orifice which is
encapsulated in the main flow.
A 3-layer thermoplastic resin sheet in which colored thermoplastic resin is
encapsulated in thermoplastic resin is obtained by using an extrusion mold
that has a manifold into which thermoplastic resin is fed, has a probe
located in said manifold that feeds colored resin into the manifold and
has a slit-shaped die orifice that serves as the extrusion sheet outlet.
The clear thermoplastic resin main flow goes into the manifold and is
extruded through the slit-shaped die extrusion mold. The colored
thermoplastic resin extruded from the wedge-shaped orifice provided in the
probe is encapsulated in the main flow of resin.
This process has the following problems.
1. Because the colored resin is extruded parallel to the flow of the main
resin, the boundary between the main resin and the colored resin
encapsulated in the main resin is clear. In other words, the edges of the
colored band are clearly visible. By giving the probe orifice a wedge
shape, the boundary between the colored band and the main flow resin can
be made a bit unclear, but there are limits to this technique.
2. Because the probe is offset to one side of the manifold, the flow of
clear thermoplastic resin sent from the manifold through to the
slit-shaped die orifice is nonuniform. The resin extrusion flow amount is
nonuniform and the sheet widthwise thickness easily becomes nonuniform.
3. Because the probe is fastened to the mold on only one side, the probe
position changes within the manifold and the colored belt shape and sheet
thickness are unstable.
SUMMARY OF THE INVENTION
This invention solves the above disadvantages and its object is to provide
a manufacturing process and apparatus for thermoplastic resin sheets in
which the edge of the colored band encapsulated in the main resin flow is
unclear.
Another object of this invention is to provide the manufacturing process
and apparatus for thermoplastic resin sheets in which the flow of resin
within the manifold is uniform.
Yet another object of this invention is to provide the manufacturing
process and apparatus for thermoplastic resin sheets in which the position
of the opening through which the colored thermoplastic resin is extruded
in the manifold does not change so that the shape of the colored band and
the sheet thickness are stable.
This invention is a process using an extrusion mold for manufacturing
thermoplastic resin sheets having along the widthwise direction a clear
resin section comprising only the clear thermoplastic resin and a colored
section in which is encapsulated a colored band comprising colored
thermoplastic resin within the first resin layer formed by the first
thermoplastic resin.
The extrusion mold has a manifold, a first thermoplastic resin passage and
a colored resin passage that feed the first thermoplastic resin and the
colored thermoplastic resin, respectively, into said manifold, a
slit-shaped die orifice through which said clear thermoplastic resin and
said colored resin are extruded out from the manifold, and a land provided
between the manifold and the slit-shaped die orifice. The first
thermoplastic resin is preferably a transparent thermoplastic resin.
This is a process in which an opening of the colored resin feed passage is
provided in a position that has flow of said first thermoplastic resin in
the widthwise direction within the manifold and that provides said colored
section and first resin section in this order in the direction of the
widthwise flow of said first thermoplastic resin. The widthwise flow of
the transparent thermoplastic resin is sufficiently great to cause at
least a portion of the colored resin to flow in a general grid-wise
direction and to cause the colored material to increase in width greater
than the width of the orifice for the colored passage, thereby to produce
a gradual transition from the colored resin to the clear resin.
Moreover, the apparatus of this invention for manufacturing thermoplastic
resin sheets is for manufacturing thermoplastic resin sheets having along
the widthwise direction a first resin section comprising only the clear
thermoplastic resin and a colored section in which a colored band
comprising the colored thermoplastic resin is encapsulated within the
first resin layer formed with the first thermoplastic resin.
The apparatus of the present invention is equipped with an extrusion mold
and cylindrical inner pipe, and said extrusion mold has a manifold, side
plates provided on both sides of the manifold widthwise, a first resin
feed passage feeding the first thermoplastic resin into the manifold, a
slit-shaped die orifice through which said first thermoplastic resin is
extruded out of the manifold, and a space provided between the manifold
and the slit-shaped die orifice.
A pipe is located within said manifold and each end of the pipe is
supported by one of said side plates.
The pipe has a colored resin feed passage that feeds colored thermoplastic
resin into the manifold. A colored resin feed passage opening is provided
in a position that has flow of the first thermoplastic resin in the
widthwise direction within the manifold. Openings for said colored resin
and first resin feed passage are located in this order in the direction of
said first thermoplastic resin widthwise flow.
The present invention preferably has an apparatus for manufacturing
thermoplastic resin sheets having along the widthwise direction a first
resin section comprising only the first clear thermoplastic resin, and a
colored section in which a colored belt comprising the colored
thermoplastic resin is encapsulated within the first clear resin layer
formed with the first thermoplastic resin.
The apparatus is equipped with an extrusion mold and a die plate, and said
extrusion mold has a manifold, a first resin feed passage feeding the
first thermoplastic resin into said manifold, a slit-shaped die orifice
through which said first thermoplastic resin is extruded out of the
manifold, and a land provided between the manifold and the slit-shaped die
orifice.
The die plate is fastened to the wall at the far end of the manifold, and
has a nozzle that feeds colored thermoplastic resin into the manifold.
The opening of the nozzle is provided in a position having flow of the
clear thermoplastic resin widthwise within the manifold. An opening for
said first resin feed passage and an opening for the colored resin feed
passage are provided in this order each extending in the direction of the
flow widthwise of said first thermoplastic resin.
An opening for feeding colored thermoplastic resin is provided at a
position where the first thermoplastic resin has a flow in a widthwise
direction within the manifold, so that the colored thermoplastic resin and
a portion of the first thermoplastic resin flow in different directions.
The outer portion of the colored thermoplastic resin that contacts the
clear thermoplastic resin is strongly affected by the main flow of the
first thermoplastic resin. The center portion of the colored resin is,
however, little affected by the main flow. Therefore the center portion of
the colored resin flows from the opening just about in the direction of
extrusion of the colored thermoplastic resin, but an outer portion of the
colored thermoplastic resin flows in a direction that is a composite of
the direction of extrusion from the orifice of the colored thermoplastic
resin and the widthwise direction of flow of the first clear thermoplastic
resin.
Since there is clear resin in the composite direction of flow of the two
resins, the colored resin is diluted with clear resin. As a result, the
width of the colored thermoplastic resin hereafter referred to as the
colored band) increases and the thickness of the colored band gradually
decreases along the widthwise direction of flow of the first clear resin.
The boundary portion (tip) of the colored band becomes extremely thin, and
a gradient portion is formed in which the colored section varies from dark
to light.
In the apparatus of the present invention, an orifice or opening in the
cylindrical inner pipe is provided at a position for feeding the colored
thermoplastic resin at a position where the first thermoplastic resin has
a flow in the widthwise direction within the manifold. The colored
thermoplastic resin being extruded from the orifice is affected by the
widthwise flow of the thermoplastic resin, thereby to produce a sheet with
a gradual color gradient.
Moreover, since the cylindrical shaped pipe runs the entire width of the
manifold, the first thermoplastic resin fed into the manifold flows
without disruption across the entire width of the manifold. In addition,
each end of the pipe is supported by one of the side boards of the
extrusion mold, so the position of the pipe opening does not change within
the manifold.
In another preferred apparatus of the present invention, an opening for
feeding the colored thermoplastic resin made in a die plate is provided at
a position where the first thermoplastic resin has a flow in the widthwise
direction within the manifold so that colored thermoplastic resin extruded
from a die plate opening is affected by the widthwise flow of the first
thermoplastic resin as described above thereby to produce a sheet with a
color gradient.
Since the die plate runs the entire width of the manifold, thermoplastic
resin fed into the manifold flows without disruption across the entire
width of the manifold. In addition, the die plate is fastened to the wall
at the far end of the manifold of the extrusion mold, so the position of
the die plate opening does not change within the manifold.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a horizontal cross section of the thermoplastic resin sheet
manufacturing apparatus for this invention.
FIG. 2 is a cross section along the line II--II in FIG. 1.
FIG. 3 is the front drawing for the manifold probe.
FIG. 4 is a diagram of the clear resin and colored resin flow.
FIGS. 5 (a)-(c) explain the working of the thermoplastic resin sheet.
FIG. 6 is a horizontal cross-section for another preferred embodiment for
the thermoplastic resin sheet manufacturing apparatus of this invention.
FIG. 7 is the cross section along the line VII--VII in FIG. 6.
FIGS. 8 (a) and (b) are the front drawing and the plane drawing. FIG. 9 is
the cross section along the line IX--IX in FIG. 8.
FIG. 10 is the horizontal cross section for another preferred embodiment of
the thermoplastic resin sheet manufacturing apparatus of this invention.
FIG. 11 is the cross section along the line XI--XI in FIG. 10.
FIGS. 12 (a) and (b) are the front and side drawings for another probe.
FIGS. 13 (a) and (b) are the front and side drawings for yet another probe.
FIG. 14 shows the dimensions of the orifice.
FIG. 15 shows the color ratio for the clear resin and the colored resin.
FIG. 16 is a graph showing the relation between the horizontal axis (the
colored band size) and the vertical axis (the color ratio).
FIG. 17 is a graph showing the relation between the horizontal axis (the
colored band size) and the vertical axis (the light transmissivity ratio).
FIG. 18 shows the dimensions of the opening.
FIG. 19 is a graph showing the relation between the horizontal axis (the
colored band size) and the vertical axis (the color ratio).
FIG. 20 is a graph showing the relation between the horizontal axis (the
colored band size) and the vertical axis (the light transmissivity ratio).
FIG. 21 shows another embodiment of this invention wherein the cylindrical
inner cylinder is placed off center within the clear extrusion.
FIG. 22 shows a graph of the width of a colored material extrusion orifice
as a function of width. In this figure, the sides are not parallel.
FIG. 23 shows a cross-sectional view of the main mold assembly of the
embodiments shown in FIGS. 21 and 22.
FIG. 24 gives actual dimensions and flow rates for the third example.
FIG. 25a shows a representation of the cross-section of the orifice from
the inner cylindrical pipe.
FIG. 25b shows a cross-section of the color melt after the material has
passed through the colored orifice and subjected to spreading and position
shift as a result of the cross-flows in the widthwise direction present in
the clear flow during merger of the two resins.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 and FIG. 2 show the apparatus for manufacturing the thermoplastic
resin sheet of this invention.
This apparatus has extrusion mold 1 and cylindrical inner pipe 2. Mold 1
comprises the manifold 3 in which the pipe 2 is located, side plates 15
and 16 along the sides of the manifold 3, the clear resin feed passage 4
which feeds the melted clear thermoplastic resin a into manifold 3, the
slit-shaped die orifice 6 that serves as the extrusion sheet outlet, and
the land 7 that serves as the resin passage through which resin is sent
from the manifold 3 to the die orifice 6.
Manifold 3 has a virtually circular cross section and runs almost the
entire width of extrusion mold 1. The inlet 41 for the first resin is at
one end of this manifold 3 and clear thermoplastic resin a is fed into the
manifold 3 from the resin extrusion apparatus (not shown in the figure)
through first resin feed passage 4 and resin inlet opening 41. When the
resin a is fed into the manifold 3 and fills the manifold 3, it moves in
the axial direction of the manifold 3, that is in the widthwise direction
of the extrusion mold 1 and is extruded from the land 7 to the slit-shaped
die orifice 6. A thermoplastic resin sheet is extruded with virtually the
same width as the manifold 3.
The cylindrical inner pipe 2 located in the above manifold 3 is virtually
cylindrical. Said cylindrical inner pipe 2 runs the entire width of the
manifold 3 and is located either concentric with the manifold 3 or
slightly toward the land 7. The two ends of the cylindrical inner pipe 2
are supported by the side plates 15, 16 mentioned above to form the gap 17
between the outer surface of the cylindrical inner pipe 2 and the inner
wall of the manifold 3 around the entire circumference.
One side (the previously mentioned resin inlet opening 41 side) of
cylindrical inner pipe 2 is empty and colored resin feed passage 5 is
located here. Said colored resin feed passage 5 opens into manifold 3 and
orifice 8 forms this opening section. Colored resin feed passage 5 is
connected to the colored thermoplastic resin extrusion apparatus (not
shown in the figure) and the colored thermoplastic resin extruded from
said extrusion apparatus flows from colored resin feed passage 5 through
the orifice 8 and into the manifold 3.
FIG. 3 shows the shape of this orifice 8. Orifice 8 comprises a rectangular
first opening 81 which is long and thin in the horizontal direction and a
triangular second opening 82 that is connected to the first opening 81 and
whose vertical dimension becomes gradually smaller. Orifice 8 is
positioned to face the land 7 previously described. The vertical gap
dimension of said orifice 8 is set smaller than the vertical gap dimension
of the slit-shaped die orifice 6. The first opening 81 of the orifice 8 is
positioned on the first resin feed passage 4 side and the second opening
82 is positioned on the opposite side. It is desirable that the length of
orifice 8 be less than half the length of slit-shaped orifice 6. A length
1/10 to 1/3 the length of slit-shaped orifice 6 is particularly desirable.
OPERATION
Clear thermoplastic resin (hereafter referred to as clear resin) (a) is fed
by an extruder into the manifold 3 through the passage 4 and the opening
41. Clear resin a fills the manifold 3 gradually from the opening 41 and
is extruded toward the outside from the land 7 to the slit-shaped die
orifice 6. In the steady state in which the clear resin (a) is fed into
the manifold 3, then extruded from the die orifice 6, the flow vectors
(resin flow direction and speed) are different at different positions
within the manifold 3, see FIG. 4.
As FIG. 4 shows, the direction for vector A of the flow of clear resin (a)
is a composite of the direction widthwise within manifold 3 and the sheet
extrusion direction. The reason why the resin widthwise flow of the clear
resin is generated within the manifold 3 is that the inflow opening 41 for
the clear resin (a) is on one section (in FIG. 1, on the left end) of the
wall of the manifold 3. Normally at the deep end of manifold 3, vector A
has a relatively large component for the resin flow in the widthwise
direction of the manifold 3 and a relatively small component for the resin
flow toward sheet extrusion. At the end close to the land 7, vector A has
a relatively small component for the resin flow in the widthwise direction
of the manifold 3 and a relatively large component for the resin flow
toward sheet extrusion. At the die orifice 6, there is almost no resin
flow widthwise across the manifold 3 and the resin flow is only in the
sheet extrusion direction.
On the other hand, the colored thermoplastic resin (hereafter referred to
as colored resin) (b) fed into colored resin feed passage 5 of the probe 2
is sent into the manifold 3 from the probe 2 orifice 8. The orifice 8 is
positioned within the manifold 3 where the widthwise flow of clear resin
(a) is generated as discussed above. Therefore, the colored resin (b)
coming out from the orifice 8 is affected by the flow of clear resin (a)
in the following manner.
The colored resin (b) fed out from the orifice flows in the direction in
which it is fed (nearly the sheet extrusion direction). The flow direction
for colored resin (b) near the orifice 8 is the sheet extrusion direction.
The flow of the portion of the colored resin (b) that encounters the clear
resin (a) is changed by the flow of the clear resin. As explained above,
since the clear resin (a) flow vector A has a component in the widthwise
direction within the manifold 3, the outer portion of colored resin (b)
(the portion near clear resin (a)) is greatly affected by the flow of
clear resin (a) and flows along vector C, which is a composite of vector B
for the original flow of colored resin (b) and vector A for the flow of
clear resin (a). The center portion of colored resin (b), which is only
slightly affected by the flow of clear resin a flows virtually in the
sheet extrusion direction.
Thus, the vectors for colored resin flow in the middle of the flow
thickness and at the edge differ, so as FIGS. 5 (a)-(c) show, the colored
band gradually becomes wider and the tip portion of the moving side of the
colored band 12 is extremely thin. Also, since there is clear resin (a) at
the outer portion of colored resin (b) in the direction it is moving,
colored resin (b) is diluted by clear resin (a). In this way and as FIG. 5
(c) shows, the sheet obtained has a first resin section 10 of only clear
resin and a colored portion 13 with three layers along its width, two No.
1 resin layers 11 made of clear resin, and the colored band 12 sandwiched
within 11. A color gradient portion 14 is formed in which the color
gradually changes from dark to light towards the first resin section 10
side.
The profile of this color gradient portion is determined by such conditions
as the location within the manifold 3 of the orifice 8 in the probe 2, the
shape and size of said orifice 8, the amount and flow speed of clear resin
(a) and colored resin (b), and the viscosities of the resins.
If the position of said probe 2 orifice 8 is moved within the manifold
toward the slit-shaped die orifice 6, then the widthwise flow component of
colored resin (b) due to clear resin (a) is minimal, so the cross section
of the gradient portion 14 resembles the shape of the opening of said
orifice 8 and the colored band 12 and the color gradient portion 14 are
both narrower. On the other hand, if the location of the orifice 8 is
moved far from the die orifice 6 within the manifold 3, then the widthwise
flow component of colored resin (b) due to clear resin (a) is large and
the colored band 12 and the color gradient portion 14 are wider. The
greater the width of the probe 2 orifice 8, the wider the colored band 12
and the color gradient portion 14.
If the ratio of the amount of colored resin (b) supplied and the amount of
clear resin (a) supplied is changed, the clear resin (a) flow vector A and
the colored resin (b) flow vector B change, so the cross-sectional shape
and the size of the colored band 12 and color gradient portion 14 formed
in the sheet change as well. It is desirable that the ratio between the
amount of colored resin (b) fed and clear resin (a) fed be between 0.5/10
and 2/10. It is also desirable that the temperatures of colored resin (b)
and of clear resin (a) be the same, but this is not absolutely necessary.
In this invention the thermoplastic resin used as clear resin (a) and as
colored resin (b) it may be, for example, polyethylene, polypropylene,
polystyrene, polycarbonate, PVC, nylon, polyvinylacetal, acrylic resin,
acetal resin, or polyester. Either the same one resin or two resins that
can blend together are selected for clear resin (a) and colored resin (b).
Plasticizers, fillers, etc. may be added to these thermoplastic resins.
For laminated glass, it is desirable that plasticized polyvinyl butyral be
used for both clear resin (a) and colored resin (b).
FIGS. 6 through 9 show another preferred embodiment. In this embodiment, a
die plate is used instead of the cylindrical inner pipe 2. Die plate 20 is
fastened at the far end of the manifold 31 and the nozzle 24 formed at the
tip of this die plate projects into the manifold 31. Said nozzle 24 runs
virtually the entire width of the manifold 31 and the end of the nozzle 24
at the first resin inlet opening 41 side is curved outward 27a to prevent
disruption of the flow of the first resin. An opening 25 is located at the
nozzle 24 resin inflow opening 41 side. As FIG. 8 shows, said opening 25
is longer sideways and has the rectangular shaped first opening 26 and the
semicircular second opening 27 and third opening 28 on either side of the
first opening 26. Compared to the second opening 27, the third opening 28
has a smaller radius of curvature and the tip of the third opening 28
projects out more than the tip of the second opening 27. The nozzle 24 has
a resin feed passage 29 for feeding colored resin (b). This resin feed
passage 29 passes through the extrusion mold 1.
The above manifold 31 is formed with a triangular cross section. Manifold
31 has three walls, of which one wall 32 is at the far side of the
manifold 31. This far side wall 32 is laid out vertically. The other two
walls, 33 and 34 connect to the top and bottom of far side wall 32 and
slant to the land 7. The front tip of these slanted walls 33 and 34 are
separated by a gap with the same dimensions as slit-shaped orifice 6. The
above nozzle 24 projects into the manifold 31 from the above far side wall
32 and the nozzle 24 divides the manifold 31 space into top and bottom. It
is desirable that the up-down dimension of the above opening 25 be no
greater than 1/2 the up-down dimension of the slit-shaped orifice 6 and a
ratio of from 1/10 to 1/3 is even better.
In this apparatus, the only point that differs from the embodiment of FIGS.
1-5 is that colored resin (b) is fed into the manifold 31 from the opening
25 provided in the die plate 20.
Colored resin (b) fed into the manifold 31 from said opening 25 is affected
by the flow of clear resin (a) within the manifold and as described above
a thermoplastic resin sheet is obtained with the colored belt 12 of
colored resin (b) encapsulated in clear resin (a). In this embodiment the
shape and dimensions of the colored band 12 are determined by such factors
as the position of the above opening 25 in the manifold 31, the shape and
size of said opening 25, the amount and speed of clear resin (a) and
colored resin (b), and the viscosities of the resins.
FIGS. 10 and 11 show another embodiment where a pipe 35, whose diameter
varies along its axis is used instead of the cylindrical inner pipe in
Example 1. From the resin inlet passage side (left side of FIG. 10) of
said pipe 35 to the right, the diameter of the pipe 35 becomes gradually
smaller. Therefore the position of the orifice 38 in this pipe is located
farther into the manifold 3 as it moves to the right side of the pipe 35.
When forming extruded sheets using this apparatus, the colored resin (b)
sent from the right side portion of the orifice 38 to the manifold 3 has a
greater flow component widthwise due to clear resin a than the colored
resin from the left side portion of the orifice 38 has, so relatively
large colored bands 12 and color gradient portions 14 can be formed.
The right side portion of the orifice 38, in particular the right side tip,
is farther into the manifold 3 than the other portions of the orifice, so
as a result, the colored resin (b) coming out of the right tip is more
affected by the widthwise flow of clear resin (a) and the tip section of
the colored band 12, (the color gradient portion 14) is thinner.
The shape of the pipe 35 can be gradually changed as FIGS. 12 and 13 show.
The pipe 2 in FIG. 12 has a circular cross section and gradually tapers to
a smaller diameter from one end to the other. The probe 2 in FIG. 13 has
an elliptical cross section.
With the process of this invention, thermoplastic resin sheets can be
obtained with colored bands as described above. In particular, since full
use is made of the widthwise flow of the clear thermoplastic resin within
the manifold, a colored band is formed having a dark color section with a
uniform dark coloration and next to that dark color a color gradient
portion that becomes lighter as it moves across the width of the sheet. It
is possible to continuously manufacture thermoplastic resin sheets with
the extrusion molding method that ar particularly useful for the colored
bands of automobile front glass. Also, with the apparatus of this
invention, the flow of resin within the manifold is uniform and
thermoplastic resin sheets can be obtained in which the colored band shape
and the sheet thickness are stable.
FIRST EXAMPLE
This apparatus was as follows:
In the extrusion mold
Left-right width of slit-shaped die orifice (6): 1000 mm,
Manifold (3)diameter: 60 mm,
Pipe diameter: 30 mm,
Resin feed passage diameter: 18 mm,
Colored resin extrusion amount/clear resin extrusion amount = 0.1, and
Temperature of the resins 150 degrees Centigrade
The shape of the probe orifice is as shown in FIG. 14 and the dimensions of
all the parts shown in FIG. 14 are as in Table 1.
The results are shown by Table 2, FIG. 16, and FIG. 17. FIG. 16 is a graph
showing the relation between the horizontal axis (the colored band size)
and the vertical axis (the color ratio, L2/L1 shown in FIG. 15). FIG. 17
is a graph showing the relation between the horizontal axis (the colored
band size) and the vertical axis (the light transmissivity ratio).
In Table 2, the color width is the width of the colored band and the shade
width shows the width of the colored band shown in FIG. 17 in which the
transmissivity ratio is 70-40%.
SECOND EXAMPLE
Thermoplastic resin sheet was extruded using the apparatus shown in FIG. 6.
In the extrusion mold
Left-right width of slit-shaped die orifice: 1000 mm,
Manifold shape: a right-angled triangle with one side of 100 mm,
Die plate nozzle thickness: 40 mm,
Resin feed passage diameter: 18 mm
Clear resin extrusion amount: 35 kg/hour,
Clear resin temperature: 150 degrees Centigrade,
Colored resin extrusion amount: 7 kg/hour, and
Colored resin temperature: 130 degrees Centigrade
As FIG. 18 and Table 3 show, there were two shapes for the opening. The
dimensions of the parts shown in FIG. 18 are as shown in Table 3. As a
result, the thermoplastic resin sheets shown in Table 3, FIG. 19, and FIG.
20 were obtained.
THIRD EXAMPLE
In FIG. 21 there is shown a cross-sectional view of another example of this
invention. The cross-sectional view 21 is similar to the cross-sectional
view 2, and similar reference numerals have been used to indicate the same
components. In this example, the radius of the clear flow first extrusion
manifold is 35 mm, the outside of the cylindrical inner pipe 2 is 19 mm,
and the inside radius of the inner pipe is 12 mm. The spacing between the
inside cylindrical pipe orifice and the entrance to the land of the
outside extrusion die is distance A which is 5 mm. In this example, the
cylindrical inner pipe is offset from the center of the main extrusion
manifold 3 in order to provide the appropriate spacing between the orifice
8 and the entrance to the land 7. This offset is 11 mm. In this example,
the width of the extrusion passage or die 6 is 1.2 to 2.5 mm (as shown at
distance C). The distance across the cylindrical inner pipe orifice is
variable in this example, and therefore the distance B will range from 0.4
to 2.6 mm.
The distance B of the orifice H shown in FIG. 21 is also shown in FIG. 22
where applicant has presented a graph of the widthwise direction against
the cylindrical pipe orifice vertical separation. Since this graph does
not appear as a straight line, it demonstrates that the sides are not
parallel as they extend in the widthwise direction of the colored orifice
opening. The dimensions given on these drawings are applicable to this
third example. In FIG. 23 there is shown a cross section of the main
extrusion mold die of example 3. In this drawing, reference numerals 3 and
7 correspond to those shown in FIG. 1. Reference numeral 40 identifies a
slidable block which is used to adjust the width of the passageway marked
E. Also shown is the pusher manifold 41 and the extrusion exit 42. The
dimensions of the mold at FIG. 23 are as follows: C=1.2 to 2.5 mm, E=3 mm,
F=14 mm, G=100 mm, H=16 mm, I=0.8 to 0.9 mm, J=20 mm, K=35 mm. In addition
to these dimensions, it should be noted that the cylindrical inner pipe 2
is located as shown in FIG. 21 where A=5 mm and the radius K equals 35 mm.
FIG. 24 gives dimensions and material flow rates for the third Example.
In FIG. 25a there is shown a cross-section of the colored orifice in the
sidewall of the cylindrical inner pipe 2. This is shown as reference
numeral 8 in FIG. 1. In this preferred embodiment, the height of the
orifice is as shown in FIG. 22. The length L is 270 mm.
In FIG. 25b there is shown a representation of the cross-section of the
final extruded color band which lies between two layers of clear resin.
The effect of the widthwise flow of the clear material upon the shape and
position of the colored material is shown in this figure. First it should
be noted that the width has been extended to a new width which is 277 mm
(dimension M). There is also a slight shift to the right of the entire
colored section which in this embodiment is 3 mm as indicated by dimension
N. FIG. 25a shows dimension O which shows the shift of the end position of
the leading edge of the color material to the right which is the sum of
the increased length of the color melt shown in FIG. 25b, (M) and the
shift N.
TABLE 1
__________________________________________________________________________
(mm)
W A R1 R2 a b c d e f
__________________________________________________________________________
Example 1
200
100
1.00
0.75
(0, 0)
(0, 2)
(100,
(100,
(200,
(200,
0) 1.75)
0) 1.50)
Example 2
200
100
1.00
0.50
(0, 0)
(0, 2)
(100,
(100,
(200,
(200,
0) 1.50)
0) 1.00)
__________________________________________________________________________
TABLE 2
______________________________________
Color Shade Ending
width width Line
______________________________________
Example 1 256 mm 16 mm .largecircle.
Example 2 255 mm 42 mm .largecircle.
______________________________________
TABLE 3
______________________________________
Shade Ending
R1 R2 width line
______________________________________
Example 3 2.0 1.5 19 mm .DELTA.
Example 4 2.0 1.0 40 mm .largecircle.
______________________________________
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